Input Junkie

Physical appearance and clothing style are near the top of the list, of course. I'm not sure whether party affiliation counts as a concrete -- it's an easily defined label, at least -- and there's been a huge jump in condemning people just for their Democratic or Republican party affiliation compared to a decade ago. Last year I received a "no Republicans" invitation to a party. I said I wasn't a Republican but still preferred not to attend such a party.